(0319) Microbiological and Clinical Characteristics of Nasopharyngeal Bacterial Infections in Patients With Postradiation Nasopharyngeal Necrosis

Introduction: Post-radiation nasopharyngeal necrosis (PRNN) significantly impacts the prognosis of nasopharyngeal cancer patients undergoing radiotherapy. This study aims to explore the microbiological features of nasopharyngeal bacterial infections in PRNN, presenting antibiotic sensitivity patterns and analyzing clinical features to guide antibiotic use.

Methods: Data from 38 PRNN patients, admitted between December 2020 and July 2022, were analyzed. Nasopharyngeal secretions were cultured for pathogen identification and sensitivity testing. The study assessed infection rates, pathogen composition, drug resistance, and sensitivity.

Results: Among 38 patients, smoking history was present in 39.5%, and three had diabetes. Of the total, 7 received secondary radiotherapy, and 34.2% exhibited symptoms of posterior cranial nerve damage, 36 (94.7%) had identified pathogens. Of the 36 positive cases, 28 (77.8%) were gram-positive bacterial infections (mainly Staphylococcus aureus in 44.4%, Streptococcus pyogenes in 4 cases, and Prevotella intermedius in 3 cases), gram-negative bacteria accounted for 41.7% (mainly Pseudomonas aeruginosa, Proteus mirabilis), anaerobic bacteria in 22.2%, facultative anaerobic bacteria in 44.4%, fungal infections in 25% (Candida albicans, tropicalis, glabrata). Single-species infection occurred in 50%, two species in 33.3%, and three species in 16.7%. Staphylococcus aureus exhibited high resistance to penicillin (87.5%), tetracycline (50%), erythromycin, and clindamycin (both 47.5%). Pseudomonas aeruginosa showed resistance rates above 75% to multiple antibiotics. Proteus mirabilis had specific resistances. Candida albicans had a 16.7% resistance to fluconazole and voriconazole. Positive culture rates showed no significant differences based on demographic or treatment variables (p > 0.05).

Conclusions: Gram-positive bacteria, especially Staphylococcus aureus, dominate nasopharyngeal infections in PRNN. The study provides insights into microbiological and drug sensitivity patterns, facilitating rational treatment guidelines for improved efficacy.